Monday, February 18, 2013

Alabama CavefishSpeoplatyrhinus poulsoniConservation status: IUCN Red List - Critically Endangered C2b; NatureServe - G1 (Alabama: S1). Listed as Endangered under the U.S. Endangered Species Act. Listed as Endangered in Alabama.Description:Speoplatyrhinus poulsoni is an eyeless and depigmented amblyopsid cavefish that is pinkish-white in color with some structures, like fins, fin rays and the venter, that are quite translucent. Morphologically, it is the most cave-adapted fish in the family Amblyopsidae. Adults are typically 30-58 mm (1.2-2.3 inches) standard length (SL). Both adults and juveniles have an extremely elongate and flattened snout with a terminal mouth that is duck-like in appearance. Unlike other amblyopsid cavefishes, S. poulsoni lacks branched fin rays, and the fin membranes are incised giving a spiked appearance. Pelvic fins are lacking. Fin rays counts are as follows: 9 (9-10) dorsal, 8 (8-9) anal, 9 (9-11) pectoral, and 22 (21-22) caudal. The lateral-line system is hypertrophied and their is an elaborated system of superficial neuromasts arranged in distinct ridges on the head and along the body. Caudal sensory papillae are also found on the caudal fin. Scales are small, imbedded, and cycloid. The urogenital pore and anus are jugular in position. Recent molecular work indicates that S. poulsoni is most closely related to the Southern Cavefish (Typhlichthys subterraneus).

Lateral view of an Alabama Cavefish.

Distribution:Speoplatyrhinus poulsoni is known from just a single cave system, Key Cave, in Lauderdale Co., Alabama, within the Tennessee River watershed. Despite numerous surveys for cavefishes in other caves in close proximity to Key Cave along the Tennessee River and elsewhere, no additional populations of S. poulsoni have been found in northwestern Alabama.Habitat: Key Cave is a maze-like cave system developed in the Mississippian-aged Tuscumbia Limestone. The aquatic habitat in Key Cave consists of a series of pools with little flow that occur in a zone of seasonal oscillation of the local water table. Several of these pools are quite deep reaching depths of up to 5 m depending on seasonal water levels. Significant bat roosts occur near at least two pools where guano occasionally slides or falls into the water.

Close-up dorsal view of head.

Natural History: Little is known regarding many aspects of the life history and ecology of S. poulsoni because of its rarity. Some
authors have speculated that females may incubate eggs and protect
young fry within the branchial chamber, based on the jugular position of
the vent. This behavior has been observed in some populations of the
related Northern Cavefish (Amblyopsis spelaea) but has yet to be demonstrated for any other amblyopsid, including S. poulsoni.
Individuals as small as 12-15 mm SL have been observed in February and
November, suggesting that S. poulsoni may breed in the summer months. In
addition, the female holotype contained developing ova and was
collected in late May, also supporting a summer spawning season. The diet of S. poulsoni has not been studied but likely includes copepods, isopods, amphipods, and perhaps small crayfish. An undescribed species of cave shrimp was recently found in Key Cave and likely is prey for S. poulsoni. Predators are unknown and its thought that S. poulsoni is one of the top consumers in the Key Cave ecosystem. Sympatry of cavefish species is rare; however, S. poulsoni cooccurs with T. subterraneus within Key Cave. Typhlichthys subterraneus is common in caves throughout central Kentucky, central Tennessee, northern Alabama, and extreme northwestern Georgia. The absence of S. poulsoni but presence of T. subterraneus from nearby cave systems suggest that competitive interactions might influence the distribution of S. poulsoni. However, this hypothesis has not been examined.

Dorsal view of an Alabama Cavefish.

Conservation:Speoplatyrhinus poulsoni is one of the rarest vertebrates in North America. The
population in Key Cave is small and no more than 10
individuals have ever been observed during a single survey.The U.S. Fish and Wildlife Service listed S. poulsoni as threatened in 1977 based on its restricted distribution, low abundance and potential threats to this species, including disturbance of a maternity colony of endangered Gray Bats (Myotis grisescens) whose guano is an important source of nutrients and energy for the aquatic ecosystem in Key Cave and groundwater pollution from pesticides as well as a proposed industrial park for the city of Florence. The threat status was later reclassified as endangered in 1988, as a sewage sludge disposal operation was found to occur within the recharge area of Key Cave. In addition, herbicide and pesticide runoff from cotton fields was found to have direct access into Key Cave via surface seeps. Loss of aquatic habitat from lowering of local groundwater levels by increased pumping also has been cited as a concern. The U.S. Fish and Wildlife Service purchased several hundred acres of land within the recharge zone of the cave and established the Key Cave National Wildlife Refuge. The agricultural land within the refuge is still maintained but cotton was replaced with corn and soybeans. In addition, all chemical use was restricted. This agricultural land is slowly being converted to upland forest and native grasslands. The most recent surveys for S. poulsoni indicate that the population is stable and recruitment is still occurring.Fun Fact:Speoplatyrhinus poulsoni is named in honor of Dr. Tom Poulson, a prominent cave biologist who has studied amblyopsid cavefishes and other cave life since the late 1950s.Select References

Tuesday, February 12, 2013

Ginny Adams and colleagues describe a new troglomorphic species of sculpin (family Cottidae) endemic to just five cave systems of the Central Perryville and Mystery-Rimstone karst in Perry County, Missouri in a recent article in Zootaxa (Adams et al. 2013). This new species, the Grotto Sculpin (Cottus specus Adams and Burr), was previously recognized as several unique troglomorphic populations of the widespread Banded Sculpin (C. carolinae) (Burr et al. 2001). Currently, C. specus is only known from cave systems and their spring resurgences in tributaries of the Bois Brule River drainage, including Cinque Hommes Creek and Blue Spring. The type-locality is Mystery Cave in Perry County, Missouri.The Grotto Sculpin can be distinguished from other members of the genus Cottus, including the closely-related C. carolinae, by reduced eyes (typically 1-5% of standard length versus 5-9% standard length) and an increase in cephalic lateralis pore size. The overall eye volume, lens and dermal cornea of the eye are also reduced in C. specus compared to C. carolinae. Pigmentation is highly variable with some individuals of C. specus lacking all apparent pigmentation in the fins and on the body, while others possess the general banding pattern of dorsal saddles typically found in C. carolinae. Cottus specus is also distinct genetically from C. carolinae based on analyses of the mitochondrial control region.Cottus specus is a species of high conservation concern. The known distribution of this cavefish is comprised of just five populations that are threatened by groundwater pollution in the form of bioaccumulative organic contaminants. Two of the five populations have experienced mass mortalities of unknown origin in the past 15 years. In addition, C. specus is generally found at much lower densities than C. carolinae, which may limit the ability of populations to recover from acute anthropogenic disturbances. Consequently, Adams et al. advocate the formal protection of C. specus at both the state state and federal level.Although not directly discussed in the paper, C. specus likely represents a cave form that has only recently colonized subterranean waters based on less elaborate troglomorphic features compared to other cavefish species in North America and levels of molecular sequence divergence between C. specus and other nearby C. carolinae populations. My interpretation is that C. specus likely colonized caves only recently sometime within the last million years, perhaps caused by or associated with climatic fluctuations during the Pleistocene.The cave and karst regions of Missouri are now home to three species of cavefishes, including Cottus specus. The other two species are the federally threatened Ozark Cavefish (Troglichthys rosae) and the Salem Plateau Cavefish (Typhlichthys eigenmanni). Typhlichthys eigenmanni was recently resurrected from T. subterraneus by Niemiller et al. (2012). Troglomorphic populations of sculpins (Cottus sp.) have been reported from Pennsylvania and West Virginia as well (Williams & Howell 1979; Espinasa & Jeffery 2003).ReferencesAdams GL, Burr BM, Day JL, Starkey DE (2013) Cottus specus, a new troglomorphic species of sculpin (Cottidae) from southeastern Missouri. Zootaxa 3609: 484-494.Burr BM, Adams GL, Krejca JK, Paul RJ, Warren Jr ML (2001) Troglomorphic sculpins of the Cottus carolinae species group in Perry County, Missouri: distribution, external morphology, and conservation status. Environmental Biology of Fishes 62: 279-296.Espinasa L, Jeffery WR (2003) A troglomorphic sculpin (Pisces: Cottidae) population: geography, morphology and conservation status. Journal of Cave and Karst Studies 65: 93-100.Niemiller ML, Near TJ, Fitzpatrick BM (2012) Delimiting species using multilocus data: diagnosing cryptic diversity in the southern cavefish Typhlichthys subterraneus (Teleostei: Amblyopsidae). Evolution 66: 846-866.Williams JD, Howell WM (1979) An albino sculpin from a cave in the New River drainage of West Virginia (Pisces: Cottidae). Brimleyana 1: 141-146.

About Me

I am an evolutionary ecologist and cave biologist who studies the evolutionary biology, ecology and conservation of subterranean organisms. I have a B.S. and M.S. from Middle Tennessee State University and a Ph.D. from the University of Tennessee. Since 2011, I have been a Gaylord Donnelley Environmental Fellow at Yale University. When not studying cave life, I enjoy spending time with my girlfriend Denise, fantasy football, and watching Indiana Hoosiers basketball.